Processes have been developed for the production of important chemicals such as propylene oxide which involve the use of dense phase or supercritical solvents such as supercritical CO2 or supercritical propane or propylene. In this regard reference is made to co-pending U.S. application Ser. No. 09/981,198 filed Oct. 16, 2001, the disclosure of which is incorporated herein in its entirety.
In such processes, the desired product can readily be recovered from the reaction mixture by decompression and vaporization of the solvent. However, for economic reasons it is necessary that the solvent be recovered and reused. Where the solvent has been vaporized in the separation, it is necessary that costly recompression and/or refrigeration procedures be used for recovery and reuse of the solvent.
The present invention provides an improved procedure whereby decompression of the reaction mixture and recompression of the solvent can be substantially avoided.